import { Injectable, BadRequestException, NotFoundException, ForbiddenException } from '@nestjs/common';
import { UserStatus, UserRole, Prisma, VerificationStatus } from '@prisma/client';
import { PrismaService } from '../prisma/prisma.service';
import { EventEmitter2 } from '@nestjs/event-emitter';
import * as argon2 from 'argon2';

type UserWithProfiles = Prisma.UserGetPayload<{
  include: { userProfile: true; agentProfile: { include: { agentType: true } } };
}>;

@Injectable()
export class UsersService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly eventEmitter: EventEmitter2,
  ) {}

  // =============================================
  // USER PROFILE METHODS (for regular users)
  // =============================================

  async getMyUserProfile(userId: string) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      include: { userProfile: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (user.role !== UserRole.USER) {
      throw new BadRequestException('This endpoint is for regular users only');
    }

    // Create user profile if it doesn't exist
    let profile = user.userProfile;
    if (!profile) {
      profile = await this.prisma.userProfile.create({
        data: {
          userId: user.id,
        },
      });
    }

    return {
      id: profile.id,
      userId: user.id,
      email: user.email,
      firstName: profile.firstName,
      lastName: profile.lastName,
      phone: profile.phone,
      avatar: profile.avatar,
      city: profile.city,
      state: profile.state,
      country: profile.country,
      createdAt: profile.createdAt,
      updatedAt: profile.updatedAt,
    };
  }

  async updateMyUserProfile(
    userId: string,
    data: {
      firstName?: string;
      lastName?: string;
      phone?: string;
      avatar?: string | null;
      city?: string;
      state?: string;
      country?: string;
    },
  ) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      include: { userProfile: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (user.role !== UserRole.USER) {
      throw new BadRequestException('This endpoint is for regular users only');
    }

    // Create or update user profile
    const profile = await this.prisma.userProfile.upsert({
      where: { userId },
      create: {
        userId,
        ...data,
      },
      update: data,
    });

    return {
      id: profile.id,
      userId: user.id,
      email: user.email,
      firstName: profile.firstName,
      lastName: profile.lastName,
      phone: profile.phone,
      avatar: profile.avatar,
      city: profile.city,
      state: profile.state,
      country: profile.country,
      createdAt: profile.createdAt,
      updatedAt: profile.updatedAt,
    };
  }

  // =============================================
  // ADMIN METHODS
  // =============================================

  async findAll(page = 1, limit = 10, role?: UserRole, search?: string, verificationStatus?: string) {
    const skip = (page - 1) * limit;

    // Build where clause
    const where: Prisma.UserWhereInput = {};
    if (role) where.role = role;
    if (search) {
      where.OR = [
        { email: { contains: search, mode: 'insensitive' } },
        { userProfile: { firstName: { contains: search, mode: 'insensitive' } } },
        { userProfile: { lastName: { contains: search, mode: 'insensitive' } } },
        { agentProfile: { firstName: { contains: search, mode: 'insensitive' } } },
        { agentProfile: { lastName: { contains: search, mode: 'insensitive' } } },
      ];
    }
    if (verificationStatus) {
      where.agentProfile = { ...((where.agentProfile as object) || {}), verificationStatus: verificationStatus as any };
    }

    const [users, total] = await Promise.all([
      this.prisma.user.findMany({
        where,
        skip,
        take: limit,
        orderBy: { createdAt: 'desc' },
        include: {
          userProfile: true,
          agentProfile: {
            include: {
              agentType: true,
            },
          },
        },
      }) as Promise<UserWithProfiles[]>,
      this.prisma.user.count({ where }),
    ]);

    return {
      users: users.map((user) => {
        // Get the appropriate profile based on role
        const profile = user.role === UserRole.AGENT ? user.agentProfile : user.userProfile;

        return {
          id: user.id,
          email: user.email,
          role: user.role,
          status: user.status,
          emailVerified: user.emailVerified,
          authProvider: user.authProvider,
          createdAt: user.createdAt,
          lastLoginAt: user.lastLoginAt,
          profile: profile
            ? {
                firstName: profile.firstName,
                lastName: profile.lastName,
                avatar: profile.avatar,
                phone: profile.phone,
                city: profile.city,
                state: profile.state,
                country: profile.country,
              }
            : null,
          agentProfile: user.agentProfile
            ? {
                id: user.agentProfile.id,
                slug: user.agentProfile.slug,
                headline: user.agentProfile.headline,
                bio: user.agentProfile.bio,
                companyName: user.agentProfile.companyName,
                licenseNumber: user.agentProfile.licenseNumber,
                yearsOfExperience: user.agentProfile.yearsOfExperience,
                isProfileComplete: user.agentProfile.isProfileComplete,
                profileCompleteness: user.agentProfile.profileCompleteness,
                agentTypeId: user.agentProfile.agentTypeId,
                agentType: user.agentProfile.agentType,
                isVerified: user.agentProfile.isVerified,
                verificationStatus: user.agentProfile.verificationStatus,
                verificationNote: user.agentProfile.verificationNote,
              }
            : null,
        };
      }),
      total,
      page,
      limit,
      totalPages: Math.ceil(total / limit),
    };
  }

  async findOne(id: string) {
    const user = (await this.prisma.user.findUnique({
      where: { id },
      include: {
        userProfile: true,
        agentProfile: {
          include: {
            agentType: true,
          },
        },
      },
    })) as UserWithProfiles | null;

    if (!user) {
      return null;
    }

    // Base user data
    const baseData = {
      id: user.id,
      email: user.email,
      role: user.role,
      status: user.status,
      emailVerified: user.emailVerified,
      emailVerifiedAt: user.emailVerifiedAt,
      authProvider: user.authProvider,
      createdAt: user.createdAt,
      lastLoginAt: user.lastLoginAt,
    };

    // For agents, return full agent profile
    if (user.role === UserRole.AGENT && user.agentProfile) {
      return {
        ...baseData,
        profile: {
          firstName: user.agentProfile.firstName,
          lastName: user.agentProfile.lastName,
          avatar: user.agentProfile.avatar,
          phone: user.agentProfile.phone,
          city: user.agentProfile.city,
          state: user.agentProfile.state,
          country: user.agentProfile.country,
        },
        agentProfile: {
          id: user.agentProfile.id,
          slug: user.agentProfile.slug,
          bio: user.agentProfile.bio,
          headline: user.agentProfile.headline,
          companyName: user.agentProfile.companyName,
          licenseNumber: user.agentProfile.licenseNumber,
          yearsOfExperience: user.agentProfile.yearsOfExperience,
          isProfileComplete: user.agentProfile.isProfileComplete,
          profileCompleteness: user.agentProfile.profileCompleteness,
          agentTypeId: user.agentProfile.agentTypeId,
          agentType: user.agentProfile.agentType,
          // Verification fields
          isVerified: user.agentProfile.isVerified,
          verificationStatus: user.agentProfile.verificationStatus,
          verificationNote: user.agentProfile.verificationNote,
          verifiedAt: user.agentProfile.verifiedAt,
          verifiedBy: user.agentProfile.verifiedBy,
        },
      };
    }

    // For regular users
    return {
      ...baseData,
      profile: user.userProfile
        ? {
            firstName: user.userProfile.firstName,
            lastName: user.userProfile.lastName,
            avatar: user.userProfile.avatar,
            phone: user.userProfile.phone,
            city: user.userProfile.city,
            state: user.userProfile.state,
            country: user.userProfile.country,
          }
        : null,
    };
  }

  async updateStatus(id: string, status: UserStatus) {
    return this.prisma.user.update({
      where: { id },
      data: { status },
    });
  }

  async updateAgentType(userId: string, agentTypeId: string) {
    // Get user to verify they are an agent
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      include: { agentProfile: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (user.role !== UserRole.AGENT) {
      throw new BadRequestException('User is not an agent');
    }

    if (!user.agentProfile) {
      throw new NotFoundException('Agent profile not found');
    }

    // Verify agent type exists
    const agentType = await this.prisma.agentType.findUnique({
      where: { id: agentTypeId },
    });

    if (!agentType) {
      throw new BadRequestException('Invalid agent type');
    }

    // Update agent profile with new agent type
    const updatedProfile = await this.prisma.agentProfile.update({
      where: { id: user.agentProfile.id },
      data: { agentTypeId },
      include: { agentType: true },
    });

    return {
      id: user.id,
      agentTypeId: updatedProfile.agentTypeId,
      agentType: updatedProfile.agentType,
      message: 'Agent type updated successfully',
    };
  }

  async getVerificationDocuments(userId: string) {
    // Get user to verify they are an agent
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      include: { agentProfile: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (user.role !== UserRole.AGENT) {
      throw new BadRequestException('User is not an agent');
    }

    if (!user.agentProfile) {
      throw new NotFoundException('Agent profile not found');
    }

    // Find the upload-documents section field
    const field = await this.prisma.profileField.findFirst({
      where: {
        section: { slug: 'upload-documents' },
        slug: 'documents',
      },
    });

    if (!field) return [];

    const fieldValue = await this.prisma.agentProfileFieldValue.findUnique({
      where: {
        agentProfileId_fieldId: {
          agentProfileId: user.agentProfile.id,
          fieldId: field.id,
        },
      },
    });

    return fieldValue?.jsonValue || [];
  }

  async updateVerification(
    userId: string,
    data: {
      status: VerificationStatus;
      note?: string;
    },
    adminId: string,
  ) {
    // Get user to verify they are an agent
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      include: { agentProfile: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (user.role !== UserRole.AGENT) {
      throw new BadRequestException('User is not an agent');
    }

    if (!user.agentProfile) {
      throw new NotFoundException('Agent profile not found');
    }

    const updateData: Prisma.AgentProfileUpdateInput = {
      verificationStatus: data.status,
      verificationNote: data.note || null,
    };

    if (data.status === VerificationStatus.APPROVED) {
      updateData.isVerified = true;
      updateData.verifiedAt = new Date();
      updateData.verifiedBy = adminId;
    } else if (data.status === VerificationStatus.REJECTED) {
      updateData.isVerified = false;
      updateData.verifiedAt = null;
      updateData.verifiedBy = null;
    }

    const updatedProfile = await this.prisma.agentProfile.update({
      where: { id: user.agentProfile.id },
      data: updateData,
      include: {
        agentType: true,
      },
    });

    // Save verification history with profile snapshot
    const profileSnapshot = await this.captureProfileSnapshot(user.agentProfile.id);
    await this.prisma.verificationHistory.create({
      data: {
        agentProfileId: user.agentProfile.id,
        status: data.status,
        note: data.note || null,
        adminId,
        submittedData: profileSnapshot ?? undefined,
      },
    });

    // Emit notification to the agent
    this.eventEmitter.emit('notification.verification', {
      recipientUserId: userId,
      status: data.status,
      note: data.note,
      agentName: `${updatedProfile.firstName || ''} ${updatedProfile.lastName || ''}`.trim(),
    });

    return {
      id: user.id,
      agentProfileId: updatedProfile.id,
      isVerified: updatedProfile.isVerified,
      verificationStatus: updatedProfile.verificationStatus,
      verificationNote: updatedProfile.verificationNote,
      verifiedAt: updatedProfile.verifiedAt,
      verifiedBy: updatedProfile.verifiedBy,
      message: `Verification ${data.status.toLowerCase()} successfully`,
    };
  }

  // Get verification history for an agent
  async getVerificationHistory(agentProfileId: string) {
    return this.prisma.verificationHistory.findMany({
      where: { agentProfileId },
      include: {
        admin: { select: { id: true, email: true } },
      },
      orderBy: { createdAt: 'desc' },
    });
  }

  // Submit or resubmit for verification (agent-facing)
  async submitForVerification(userId: string) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      include: { agentProfile: true },
    });

    if (!user) throw new NotFoundException('User not found');
    if (user.role !== UserRole.AGENT) throw new BadRequestException('User is not an agent');
    if (!user.agentProfile) throw new NotFoundException('Agent profile not found');

    const currentStatus = user.agentProfile.verificationStatus;
    if (currentStatus === VerificationStatus.PENDING_REVIEW) {
      throw new BadRequestException('Verification is already pending review');
    }
    if (currentStatus === VerificationStatus.APPROVED) {
      throw new BadRequestException('Profile is already verified');
    }

    // Capture snapshot of current profile data + documents
    const profileSnapshot = await this.captureProfileSnapshot(user.agentProfile.id);

    // Update status to PENDING_REVIEW
    await this.prisma.agentProfile.update({
      where: { id: user.agentProfile.id },
      data: {
        verificationStatus: VerificationStatus.PENDING_REVIEW,
        verificationNote: null,
      },
    });

    // Create history entry with submitted data snapshot
    await this.prisma.verificationHistory.create({
      data: {
        agentProfileId: user.agentProfile.id,
        status: VerificationStatus.PENDING_REVIEW,
        note: currentStatus === VerificationStatus.REJECTED ? 'Resubmitted after rejection' : 'Initial submission',
        submittedData: profileSnapshot ?? undefined,
      },
    });

    return { message: 'Verification submitted successfully', status: 'PENDING_REVIEW' };
  }

  // Capture a snapshot of agent's profile data and documents for history
  private async captureProfileSnapshot(agentProfileId: string) {
    const profile = await this.prisma.agentProfile.findUnique({
      where: { id: agentProfileId },
      include: {
        user: { select: { email: true } },
        agentType: { select: { id: true, name: true } },
        fieldValues: {
          include: {
            field: {
              select: { slug: true, name: true, fieldType: true, section: { select: { slug: true, name: true } } },
            },
          },
        },
      },
    });

    if (!profile) return null;

    // Organize field values by section
    const sections: Record<string, Record<string, any>> = {};
    for (const fv of profile.fieldValues) {
      const sectionSlug = fv.field.section.slug;
      if (!sections[sectionSlug]) {
        sections[sectionSlug] = { _name: fv.field.section.name };
      }
      const value = fv.textValue ?? fv.numberValue ?? fv.booleanValue ?? fv.jsonValue ?? fv.dateValue;
      sections[sectionSlug][fv.field.slug] = {
        name: fv.field.name,
        type: fv.field.fieldType,
        value,
      };
    }

    return {
      firstName: profile.firstName,
      lastName: profile.lastName,
      email: profile.user?.email,
      phone: profile.phone,
      avatar: profile.avatar,
      bio: profile.bio,
      agentType: profile.agentType?.name,
      sections,
      capturedAt: new Date().toISOString(),
    };
  }

  // Check which required fields are missing for an agent
  private async getRequiredFieldsMissing(agentProfileId: string, agentTypeId: string | null) {
    // Get all sections for this agent type (or global sections)
    const sectionFilter: any = { isActive: true };
    if (agentTypeId) {
      sectionFilter.OR = [
        { isGlobal: true },
        { agentTypeSections: { some: { agentTypeId } } },
      ];
    } else {
      sectionFilter.isGlobal = true;
    }

    // Get all required fields from applicable sections
    const requiredFields = await this.prisma.profileField.findMany({
      where: {
        isRequired: true,
        isActive: true,
        section: sectionFilter,
      },
      select: { id: true, name: true, slug: true, section: { select: { name: true, slug: true } } },
    });

    if (requiredFields.length === 0) return [];

    // Get agent's filled field values
    const filledValues = await this.prisma.agentProfileFieldValue.findMany({
      where: {
        agentProfileId,
        fieldId: { in: requiredFields.map((f) => f.id) },
      },
      select: { fieldId: true, textValue: true, numberValue: true, booleanValue: true, jsonValue: true, dateValue: true },
    });

    const filledMap = new Map(filledValues.map((fv) => [fv.fieldId, fv]));

    // Find missing or empty required fields
    const missing: { fieldName: string; sectionName: string }[] = [];
    for (const field of requiredFields) {
      const value = filledMap.get(field.id);
      if (!value) {
        missing.push({ fieldName: field.name, sectionName: field.section.name });
        continue;
      }
      // Check if value is actually empty
      const hasValue = value.textValue || value.numberValue !== null || value.booleanValue !== null ||
        (value.jsonValue && (Array.isArray(value.jsonValue) ? (value.jsonValue as any[]).length > 0 : true)) ||
        value.dateValue;
      if (!hasValue) {
        missing.push({ fieldName: field.name, sectionName: field.section.name });
      }
    }

    return missing;
  }

  // =============================================
  // NOTIFICATION PREFERENCES
  // =============================================

  async getNotificationPreferences(userId: string) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      select: { notificationPreferences: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    // Return preferences or default empty object
    return user.notificationPreferences || { email: {}, push: {} };
  }

  async updateNotificationPreferences(
    userId: string,
    preferences: { email?: Record<string, boolean>; push?: Record<string, boolean> },
  ) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    const updatedUser = await this.prisma.user.update({
      where: { id: userId },
      data: {
        notificationPreferences: preferences,
      },
      select: { notificationPreferences: true },
    });

    return updatedUser.notificationPreferences;
  }

  // =============================================
  // PRIVACY PREFERENCES
  // =============================================

  async getPrivacyPreferences(userId: string) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      select: { privacyPreferences: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    // Return preferences or default empty object
    return user.privacyPreferences || { privacySettings: {}, dataSettings: {} };
  }

  async updatePrivacyPreferences(
    userId: string,
    preferences: {
      privacySettings?: Record<string, string>;
      dataSettings?: Record<string, boolean>;
    },
  ) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    const updatedUser = await this.prisma.user.update({
      where: { id: userId },
      data: {
        privacyPreferences: preferences,
      },
      select: { privacyPreferences: true },
    });

    return updatedUser.privacyPreferences;
  }

  // =============================================
  // DELETE ACCOUNT
  // =============================================

  async deleteAccount(userId: string) {
    const user = await this.prisma.user.findUnique({
      where: { id: userId },
      select: { id: true, role: true },
    });

    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (user.role !== UserRole.USER) {
      throw new BadRequestException('This endpoint is for regular users only');
    }

    // Delete in a transaction to ensure data consistency
    await this.prisma.$transaction(async (tx) => {
      // Delete user profile if it exists
      await tx.userProfile.deleteMany({
        where: { userId },
      });

      // Delete the user account
      await tx.user.delete({
        where: { id: userId },
      });
    });

    return { message: 'Account deleted successfully' };
  }

  // =============================================
  // ADMIN MANAGEMENT (SUPER_ADMIN only)
  // =============================================

  async getAdminUsers() {
    return this.prisma.user.findMany({
      where: { role: { in: ['ADMIN', 'SUPER_ADMIN'] } },
      select: {
        id: true,
        email: true,
        role: true,
        status: true,
        createdAt: true,
        lastLoginAt: true,
      },
      orderBy: { createdAt: 'desc' },
    });
  }

  async createAdminUser(email: string, password: string) {
    const existing = await this.prisma.user.findUnique({ where: { email } });
    if (existing) {
      throw new BadRequestException('A user with this email already exists');
    }

    const hashedPassword = await argon2.hash(password);
    return this.prisma.user.create({
      data: {
        email,
        password: hashedPassword,
        role: 'ADMIN',
        status: 'ACTIVE',
        emailVerified: true,
        emailVerifiedAt: new Date(),
        authProvider: 'LOCAL',
      },
      select: {
        id: true,
        email: true,
        role: true,
        status: true,
        createdAt: true,
      },
    });
  }

  async deleteAdminUser(id: string, requesterId: string) {
    if (id === requesterId) {
      throw new BadRequestException('You cannot delete your own account');
    }

    const user = await this.prisma.user.findUnique({ where: { id } });
    if (!user) throw new NotFoundException('User not found');
    if (user.role === 'SUPER_ADMIN') {
      throw new ForbiddenException('Cannot delete a super admin');
    }
    if (user.role !== 'ADMIN') {
      throw new BadRequestException('This user is not an admin');
    }

    await this.prisma.user.delete({ where: { id } });
    return null;
  }
}